Re: [PATCH 2/8] commit-graph.c: show progress of finding reachable commits

On Tue, May 05, 2020 at 07:50:50AM -0400, Derrick Stolee wrote:

On 5/4/2020 9:13 PM, Taylor Blau wrote:

quoted

When 'git commit-graph write --reachable' is invoked, the commit-graph
machinery calls 'for_each_ref()' to discover the set of reachable
commits.

Right now the 'add_ref_to_set' callback is not doing anything other than
adding an OID to the set of known-reachable OIDs. In a subsequent
commit, 'add_ref_to_set' will presumptively peel references. This
operation should be fast for repositories with an up-to-date
'$GIT_DIR/packed-refs', but may be slow in the general case.

So that it doesn't appear that 'git commit-graph write' is idling with
'--reachable' in the slow case, add a progress meter to provide some
output in the meantime.

In general, we don't expect a progress meter to appear at all, since
peeling references with a 'packed-refs' file is quick. If it's slow and
we do show a progress meter, the subsequent 'fill_oids_from_commits()'
will be fast, since all of the calls to
'lookup_commit_reference_gently()' will be no-ops.

Both progress meters are delayed, so it is unlikely that more than one
will appear. In either case, this intermediate state will go away in a
handful of patches, at which point there will be at most one progress
meter.

Signed-off-by: Taylor Blau <redacted>
---
 commit-graph.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/commit-graph.c b/commit-graph.c
index 00da281f39..8f61256b0a 100644
--- a/commit-graph.c
+++ b/commit-graph.c

@@ -1320,6 +1320,7 @@ static void compute_bloom_filters(struct write_commit_graph_context *ctx)

 struct refs_cb_data {
 	struct oidset *commits;
+	struct progress *progress;
 };

 static int add_ref_to_set(const char *refname,

@@ -1328,6 +1329,8 @@ static int add_ref_to_set(const char *refname,
 {
 	struct refs_cb_data *data = (struct refs_cb_data *)cb_data;

+	display_progress(data->progress, oidset_size(data->commits) + 1);
+
 	oidset_insert(data->commits, oid);
 	return 0;
 }

@@ -1342,12 +1345,17 @@ int write_commit_graph_reachable(struct object_directory *odb,

 	memset(&data, 0, sizeof(data));
 	data.commits = &commits;
+	if (flags & COMMIT_GRAPH_WRITE_PROGRESS)
+		data.progress = start_delayed_progress(
+			_("Finding reachable commits"), 0);

Is this the right phrase to use? This seems too close to the progress
indicator "Expanding reachable commits in commit graph" which is walking
commits.

An alternative could be: "Collecting referenced commits"

That's a great suggestion. I'll apply that locally. For what it's worth,
I don't feel that strongly about it either, but it's not hard to change
;).

Outside of this string, I have no complaints. I also don't feel too
strongly about the string, either.

Thanks,
-Stolee

Thanks,
Taylor